21.6: Small and Large Intestines
By the end of the section, you will be able to:
- Compare and contrast the location and gross anatomy of the small and large intestines
- Identify three main adaptations of the small intestine wall that increase its absorptive capacity
- Describe the mechanical and chemical digestion of chyme upon its release into the small intestine
- List three features unique to the wall of the large intestine and identify their contributions to its function
- Identify the beneficial roles of the bacterial flora in digestive system functioning
- Trace the pathway of food waste from its point of entry into the large intestine through its exit from the body as feces
The word intestine is derived from a Latin root meaning “internal,” and indeed, the two organs together nearly fill the interior of the abdominal cavity. In addition, called the small and large bowel, or colloquially the “guts,” they constitute the greatest mass and length of the alimentary canal and, with the exception of ingestion, perform all digestive system functions.
Small Intestine
Chyme released from the stomach enters the small intestine , which is the primary digestive organ in the body. Not only is this where most digestion occurs, it is also where practically all absorption occurs. The longest part of the alimentary canal, the small intestine is about 3.05 meters (10 feet) long in a living person (but about twice as long in a cadaver due to the loss of muscle tone). Since this makes it about five times longer than the large intestine, you might wonder why it is called “small.” In fact, its name derives from its relatively smaller diameter of only about 2.54 cm (1 in), compared with 7.62 cm (3 in) for the large intestine. As we’ll see shortly, in addition to its length, the folds and projections of the lining of the small intestine work to give it an enormous surface area, which is approximately 200 m 2 , more than 100 times the surface area of your skin. This large surface area is necessary for complex processes of digestion and absorption that occur within it.
Structure
The coiled tube of the small intestine is subdivided into three regions. From proximal (at the stomach) to distal, these are the duodenum, jejunum, and ileum (Figure 21.6.1). The shortest region is the 25.4-cm (10-in) duodenum , which begins at the pyloric sphincter. Just past the pyloric sphincter, it bends posteriorly behind the peritoneum, becoming retroperitoneal, and then makes a C-shaped curve around the head of the pancreas before ascending anteriorly again to return to the peritoneal cavity and join the jejunum. The duodenum can therefore be subdivided into four segments: the superior, descending, horizontal, and ascending duodenum.
Of particular interest is the hepatopancreatic ampulla (ampulla of Vater). Located in the duodenal wall, the ampulla marks the transition from the anterior portion of the alimentary canal to the mid-region, and is where the bile duct (through which bile passes from the liver) and the main pancreatic duct (through which pancreatic juice passes from the pancreas) join. This ampulla opens into the duodenum at a tiny volcano-shaped structure called the major duodenal papilla . The hepatopancreatic sphincter (sphincter of Oddi) regulates the flow of both bile and pancreatic juice from the ampulla into the duodenum.
The jejunum is about 0.9 meters (3 feet) long (in life) and runs from the duodenum to the ileum. Jejunum means “empty” in Latin and supposedly was so named by the ancient Greeks who noticed it was always empty at death. No clear demarcation exists between the jejunum and the final segment of the small intestine, the ileum.
The ileum is the longest part of the small intestine, measuring about 1.8 meters (6 feet) in length. It is thicker, more vascular, and has more developed mucosal folds than the jejunum. The ileum joins the cecum, the first portion of the large intestine, at the ileocecal sphincter (or valve). The jejunum and ileum are tethered to the posterior abdominal wall by the mesentery. The large intestine frames these three parts of the small intestine.
Parasympathetic nerve fibers from the vagus nerve and sympathetic nerve fibers from the thoracic splanchnic nerve provide extrinsic innervation to the small intestine. The superior mesenteric artery is its main arterial supply. Veins run parallel to the arteries and drain into the superior mesenteric vein. Nutrient-rich blood from the small intestine is then carried to the liver via the hepatic portal vein.
Histology
The wall of the small intestine is composed of the same four layers typically present in the alimentary system. However, three features of the mucosa and submucosa are unique. These features, which increase the absorptive surface area of the small intestine more than 600 times, include circular folds ( plicae circulares ), villi, and microvilli (Figure 21.6.2). These adaptations are most abundant in the proximal two-thirds of the small intestine, where the majority of absorption occurs.
Circular folds
Also called a plica circulare, a circular fold is a deep ridge in the mucosa and submucosa. These plicae circulares form transverse ridges that can be up to 1 cm in depth and are visible to the naked eye. Beginning near the proximal part of the duodenum and ending near the middle of the ileum, these folds facilitate absorption. In addition to increasing the surface area, their shape causes the chyme to spiral, rather than move in a straight line, through the small intestine. Spiraling slows the movement of chyme and provides the time needed for nutrients to be fully absorbed.
Villi
Within the circular folds are small (0.5–1 mm long) hairlike vascularized projections called villi (singular = villus) that give the mucosa a furry texture. There are about 20 to 40 villi per square millimeter, increasing the surface area of the epithelium tremendously. The mucosal simple columnar epithelium, primarily composed of absorptive cells, covers the villi. In addition to muscle and connective tissue to support its structure, each villus contains a capillary bed composed of one arteriole and one venule, as well as a lymphatic capillary called a lacteal . The breakdown products of carbohydrates and proteins (sugars and amino acids) can enter the bloodstream directly, but lipid breakdown products are absorbed by the lacteals and transported to the bloodstream via the lymphatic system.
Microvilli
As their name suggests, microvilli (singular = microvillus) are much smaller (1 µ m) than villi. They are cylindrical apical surface extensions of the plasma membrane of the mucosa’s epithelial cells, and are supported by microfilaments within those cells. Although their small size makes it difficult to see each microvillus, their combined microscopic appearance suggests a mass of bristles, which is termed the brush border . Fixed to the surface of the microvilli membranes are enzymes that finish digesting carbohydrates and proteins and in some cases transporter proteins to aid in digestion. There are an estimated 200 million microvilli per square millimeter of small intestine, greatly expanding the surface area of the plasma membrane and thus greatly enhancing absorption.
Intestinal Glands
In addition to the three specialized absorptive features just discussed, the mucosa between the villi is dotted with deep crevices that each lead into a tubular intestinal gland (crypt of Lieberkühn), which is formed by cells that line the crevices (Figure 21.6.2). These produce intestinal juice , a slightly alkaline (pH 7.4 to 7.8) mixture of water and mucus. Each day, about 0.95 to 1.9 liters (1 to 2 quarts) are secreted in response to the distention of the small intestine or the irritating effects of chyme on the intestinal mucosa. In addition to the exocrine glands making intestinal juice, there are enteroendocrine cells to secrete many regulatory hormones that communicate with other digestive organs including the pancreas and gallbladder.
The submucosa of the duodenum is the only site of the complex mucus-secreting duodenal glands (Brunner’s glands), which produce a bicarbonate-rich alkaline mucus that buffers the acidic chyme as it enters from the stomach.
The lamina propria of the small intestine mucosa is studded with quite a bit of mucosa associated lymphoid tissue (MALT). In addition to solitary lymphatic nodules, aggregations of intestinal MALT, which are typically referred to as Peyer’s patches, are concentrated in the distal ileum, and serve to keep bacteria from entering the bloodstream. Peyer’s patches are most prominent in young people and become less distinct as you age, which coincides with the general activity of our immune system.
Digestive Functions of the Small Intestine
Mechanical Digestion
The movement of intestinal smooth muscles includes both segmentation and a form of peristalsis called migrating motility complexes. The kind of peristaltic mixing waves seen in the stomach are not observed here.
If you could see into the small intestine when it was going through segmentation, it would look as if the contents were being shoved incrementally back and forth, as the rings of smooth muscle repeatedly contract and then relax. Segmentation in the small intestine does not force chyme through the tract. Instead, it combines the chyme with digestive juices and pushes food particles against the mucosa to be digested and absorbed. The duodenum is where the most rapid segmentation occurs, at a rate of about 12 times per minute. In the ileum, segmentations are only about eight times per minute (Figure 21.6.3). Figure 21.6.3 is a drawing of the small intestine undergoing segmentation with alternating constriction and relaxation of the smooth muscles to mix and move the contents inside.
When most of the chyme has been absorbed, the small intestinal wall becomes less distended. At this point, the localized segmentation process is replaced by transport movements. The duodenal mucosa secretes the hormone motilin , which initiates peristalsis in the form of a migrating motility complex . These complexes, which begin in the duodenum, force chyme through a short section of the small intestine and then stop. The next contraction begins a little bit farther down than the first, forces chyme a bit farther through the small intestine, then stops. These complexes move slowly down the small intestine, forcing chyme on the way, taking around 90 to 120 minutes to finally reach the end of the ileum. At this point, the process is repeated, starting in the duodenum.
The ileocecal valve, a sphincter, is usually in a constricted state, but when motility in the ileum increases, this sphincter relaxes, allowing food residue to enter the first portion of the large intestine, the cecum. Relaxation of the ileocecal sphincter is controlled by both nerves and hormones. First, digestive activity in the stomach provokes the gastroileal reflex , which increases the force of ileal segmentation. Second, the stomach releases the hormone gastrin, which enhances ileal motility, thus relaxing the ileocecal sphincter. After chyme passes through, backward pressure helps close the sphincter, preventing backflow into the ileum.  It takes about 3 to 5 hours for all chyme to leave the small intestine.
Chemical Digestion
The digestion of proteins and carbohydrates, which partially occurs in the stomach, is completed in the small intestine with the aid of intestinal and pancreatic juices. Pancreatic and brush border enzymes continue and complete chemical digestion of carbohydrates and proteins. Lipids arrive in the intestine largely undigested, so much of the focus here is on lipid digestion, which is facilitated by bile and the enzyme pancreatic lipase.
Moreover, intestinal juice combines with pancreatic juice to provide a liquid medium that facilitates absorption. The intestine is also where most water is absorbed, via osmosis. The small intestine’s absorptive cells also synthesize digestive enzymes and then place them in the plasma membranes of the microvilli. This distinguishes the small intestine from the stomach; that is, enzymatic digestion occurs not only in the lumen, but also on the luminal surfaces of the mucosal cells.
For optimal chemical digestion, chyme must be delivered from the stomach slowly and in small amounts. This is because chyme from the stomach is typically hypertonic (higher concentration than the content in small intestine), and if large quantities were forced all at once into the small intestine, the resulting osmotic water loss from the blood into the intestinal lumen, to dilute the chyme, would result in potentially life-threatening low blood volume. In addition, continued digestion requires an upward adjustment of the low pH of stomach chyme, along with rigorous mixing of the chyme with bile and pancreatic juices. Both processes take time, so the pumping action of the pylorus must be carefully controlled to prevent the duodenum from being overwhelmed with chyme.
DISORDERS OF THE...
Digestive System: Lactose Intolerance
Lactose intolerance is a condition characterized by indigestion caused by dairy products. It occurs when the absorptive cells of the small intestine do not produce enough lactase, the enzyme that digests the milk sugar lactose. In most mammals, lactose intolerance increases with age. In contrast, some human populations, most notably Caucasians, are able to maintain the ability to produce lactase as adults.
In people with lactose intolerance, the lactose in chyme is not digested. Bacteria in the large intestine ferment the undigested lactose, a process that produces gas. In addition to gas, symptoms include abdominal cramps, bloating, and diarrhea. Symptom severity ranges from mild discomfort to severe pain; however, symptoms resolve once the lactose is eliminated in feces.
The hydrogen breath test is used to help diagnose lactose intolerance. Lactose-tolerant people have very little hydrogen in their breath. Those with lactose intolerance exhale hydrogen, which is one of the gases produced by the bacterial fermentation of lactose in the colon. After the hydrogen is absorbed from the intestine, it is transported through blood vessels into the lungs. There are a number of lactose-free dairy products available in grocery stores. In addition, dietary supplements are available. Taken with food, they provide lactase to help digest lactose.
Large Intestine
The large intestine is the terminal part of the alimentary canal. The primary function of this organ is to finish absorption of nutrients and water, synthesize certain vitamins, form feces, and eliminate feces from the body.
Structure
The large intestine runs from the appendix to the anus. It frames the small intestine on three sides. Despite its being about one-half as long as the small intestine, it is called large because it has a diameter that is more than twice the diameter of the small intestine, about 3 inches. The large intestine is subdivided into four main regions: the cecum, the colon, the rectum, and the anus. The ileocecal valve, located at the opening between the ileum and the large intestine, controls the flow of chyme from the small intestine to the large intestine.
Cecum
The first part of the large intestine is the cecum , a sac-like structure that is suspended inferior to the ileocecal valve. It is about 6 cm (2.4 in) long, receives the contents of the ileum, and continues the absorption of water and salts. The appendix (or vermiform appendix) is a winding, dead-end tube that attaches to the cecum. Although the 7.6-cm (3-in) long appendix contains lymphoid tissue, suggesting an immunologic function, this organ is generally considered vestigial (a structure present in our ancestors that has over time lost its original function). However, at least one recent report postulates a survival advantage conferred by the appendix: In diarrheal illness, the appendix may serve as a bacterial reservoir to repopulate the enteric bacteria for those surviving the initial phases of the illness. Moreover, its twisted anatomy provides a haven for the accumulation and multiplication of enteric bacteria. The mesoappendix , the mesentery of the appendix, tethers it to the mesentery of the ileum.
Colon
The cecum blends seamlessly with the colon . The small intestine is faintly superimposed to show the location of both the large and small intestines. Upon entering the colon, the food residue first travels up the ascending colon on the right side of the abdomen. At the inferior surface of the liver, the colon bends to form the right colic flexure (hepatic flexure) and becomes the transverse colon . The region defined as hindgut begins with the last third of the transverse colon and continues on. Food residue passing through the transverse colon travels across to the left side of the abdomen, where the colon angles sharply immediately inferior to the spleen, at the left colic flexure (splenic flexure). From there, food residue passes through the descending colon , which runs down the left side of the posterior abdominal wall. After entering the pelvis inferiorly, it becomes the s-shaped sigmoid colon , which extends medially to the midline (Figure 21.6.4). The ascending and descending colon, and the rectum (discussed next) are located in the retroperitoneum. The transverse and sigmoid colon are tethered to the posterior abdominal wall by the mesocolon.
DISORDER OF THE...
Digestive System: Colorectal Cancer
Each year, approximately 140,000 Americans are diagnosed with colorectal cancer, and another 49,000 die from it, making it one of the most deadly malignancies. People with a family history of colorectal cancer are at increased risk. Smoking, excessive alcohol consumption, and a diet high in animal fat and protein also increase the risk. Despite popular opinion to the contrary, studies support the conclusion that dietary fiber and calcium do not reduce the risk of colorectal cancer.
Colorectal cancer may be signaled by constipation or diarrhea, cramping, abdominal pain, and rectal bleeding. Bleeding from the rectum may be either obvious or occult (hidden in feces). Since most colon cancers arise from benign mucosal growths called polyps, cancer prevention is focused on identifying these polyps. The colonoscopy is both diagnostic and therapeutic. Colonoscopy not only allows identification of precancerous polyps, the procedure also enables them to be removed before they become malignant. Screening for fecal occult blood tests and colonoscopy is recommended for those over 50 years of age.
Rectum
Food residue leaving the sigmoid colon enters the rectum in the pelvis, near the third sacral vertebra. The final 20.3 cm (8 in) of the alimentary canal, the rectum extends anterior to the sacrum and coccyx. Even though rectum is Latin for “straight,” this structure follows the curved contour of the sacrum and has three lateral bends that create a trio of internal transverse folds called the rectal valves . These valves help separate the feces from gas to prevent the simultaneous passage of feces and gas.
Anal Canal
Finally, food residue reaches the last part of the large intestine, the anal canal , which is located in the perineum, completely outside of the abdominopelvic cavity. This 3.8–5 cm (1.5–2 in) long structure opens to the exterior of the body at the anus. The anal canal includes two sphincters. The internal anal sphincter is made of smooth muscle, and its contractions are involuntary. The external anal sphincter is made of skeletal muscle, which is under voluntary control. Except when defecating, both usually remain closed.
Histology
There are several notable differences between the walls of the large and small intestines (Figure 21.6.5). For example, few enzyme-secreting cells are found in the wall of the large intestine, and there are no circular folds or villi. Other than in the anal canal, the mucosa of the colon is simple columnar epithelium made mostly of absorptive enterocytes with microvilli and goblet cells. In addition, the mucosa has far more intestinal glands, which contain a vast population of enterocytes and goblet cells. These goblet cells secrete mucus that eases the movement of feces and protects the intestine from the effects of the acids and gases produced by enteric bacteria. The enterocytes absorb water and salts as well as vitamins produced by your intestinal bacteria.
Structural Features
The teniae coli are three bands of smooth muscle that make up the longitudinal muscle layer of the muscularis of the large intestine, except at its terminal end. Tonic contractions of the teniae coli bunch up the colon into a succession of pouches called haustra (singular = hostrum), which are responsible for the wrinkled appearance of the colon. Attached to the teniae coli are small, fat-filled sacs of visceral peritoneum called epiploic appendages . The purpose of these is unknown. Although the rectum and anal canal have neither teniae coli nor haustra, they do have well-developed layers of muscularis that create the strong contractions needed for defecation.
 This mucosa varies considerably from that of the rest of the colon to accommodate the high level of abrasion as feces pass through.
 The pectinate line (or dentate line) is a horizontal, jagged band that runs circumferentially just below the level of the anal sinuses, and represents the junction between the hindgut and external skin. The mucosa above this line is fairly insensitive, whereas the area below is very sensitive. The resulting difference in pain threshold is due to the fact that the upper region is innervated by visceral sensory fibers, and the lower region is innervated by somatic sensory fibers.
Bacterial Flora
Most bacteria that enter the alimentary canal are killed by lysozyme, defensins, HCl, or protein-digesting enzymes. However, trillions of bacteria live within the large intestine and are referred to as the bacterial flora . Most of the more than 700 species of these bacteria are nonpathogenic commensal organisms that cause no harm as long as they stay in the gut lumen. In fact, many facilitate chemical digestion and absorption, and some synthesize certain vitamins, mainly biotin, pantothenic acid, and vitamin K. Some are linked to increased immune response. A refined system prevents these bacteria from crossing the mucosal barrier.
Digestive Functions of the Large Intestine
The residue of chyme that enters the large intestine contains few nutrients except water, which is reabsorbed as the residue lingers in the large intestine, typically for 12 to 24 hours. Thus, it may not surprise you that the large intestine can be completely removed without significantly affecting digestive functioning. For example, in severe cases of inflammatory bowel disease, the large intestine can be removed by a procedure known as a colectomy. Often, a new fecal pouch can be crafted from the small intestine and sutured to the anus, but if not, an ileostomy can be created by bringing the distal ileum through the abdominal wall, allowing the watery chyme to be collected in a bag-like adhesive appliance.
Mechanical Digestion
In the large intestine, mechanical digestion begins when chyme moves from the ileum into the cecum, an activity regulated by the ileocecal sphincter. Right after you eat, peristalsis in the ileum forces chyme into the cecum. When the cecum is distended with chyme, contractions of the ileocecal sphincter strengthen to prevent backflow. Once chyme enters the cecum, colon movements begin.
Mechanical digestion in the large intestine includes a combination of three types of movements. The presence of food residues in the colon stimulates a slow-moving haustral contraction . This type of movement involves sluggish segmentation, primarily in the transverse and descending colons. When a haustrum is distended with chyme, its muscle contracts, pushing the residue into the next haustrum. These contractions occur about every 30 minutes, and each last about 1 minute. These movements also mix the food residue, which helps the large intestine absorb water. The second type of movement is peristalsis, which, in the large intestine, is slower than in the more proximal portions of the alimentary canal. The third type is a mass movement . These strong waves start midway through the transverse colon and quickly force the contents toward the rectum.  Distension in the stomach and the breakdown products of digestion in the small intestine provoke the gastrocolic reflex , which increases motility, including mass movements, in the colon. Fiber in the diet both softens the stool and increases the power of colonic contractions, optimizing the activities of the colon.
Chemical Digestion
Although the glands of the large intestine secrete mucus, they do not secrete digestive enzymes. Therefore, chemical digestion in the large intestine occurs exclusively because of bacteria in the lumen of the colon. Through the process of saccharolytic fermentation , bacteria break down some of the remaining carbohydrates. This results in the discharge of hydrogen, carbon dioxide, and methane gases that create flatus (gas) in the colon; flatulence is excessive flatus. Each day, up to 1500 mL of flatus is produced in the colon. More is produced when you eat foods such as beans, which are rich in otherwise indigestible sugars and complex carbohydrates like soluble dietary fiber.
Absorption, Feces Formation, and Defecation
The small intestine absorbs about 90 percent of the water you ingest (either as liquid or within solid food). The large intestine absorbs most of the remaining water, a process that converts the liquid chyme residue into semisolid feces (“stool”). Feces is composed of undigested food residues, unabsorbed digested substances, millions of bacteria, old epithelial cells from the GI mucosa, inorganic salts, other waste products, and enough water to let it pass smoothly out of the body. Of every 500 mL (17 ounces) of food residue that enters the cecum each day, about 150 mL (5 ounces) become feces.
The process of defecation begins when mass movements force feces from the colon into the rectum, stretching the rectal wall and provoking the defecation reflex, which eliminates feces from the rectum. This parasympathetic reflex is mediated by the spinal cord.   If you decide to delay defecation, it takes a few seconds for the reflex contractions to stop and the rectal walls to relax. The next mass movement will trigger additional defecation reflexes until you defecate.
If defecation is delayed for an extended time, additional water is absorbed, making the feces firmer and potentially leading to constipation. On the other hand, if the waste matter moves too quickly through the intestines, not enough water is absorbed, and diarrhea can result. This can be caused by the ingestion of foodborne pathogens. In general, diet, health, and stress determine the frequency of bowel movements. The number of bowel movements varies greatly between individuals, ranging from two or three per day to three or four per week.
Concept Review
The three main regions of the small intestine are the duodenum, the jejunum, and the ileum. The small intestine is where digestion is completed and virtually all absorption occurs. These two activities are facilitated by structural adaptations that increase the mucosal surface area by 600-fold, including circular folds, villi, and microvilli. There are around 200 million microvilli per square millimeter of small intestine, which contain brush border enzymes that complete the digestion of carbohydrates and proteins. Combined with pancreatic juice, intestinal juice provides the liquid medium needed to further digest and absorb substances from chyme. The small intestine is also the site of unique mechanical digestive movements. Segmentation moves the chyme back and forth, increasing mixing and opportunities for absorption. Migrating motility complexes propel the residual chyme toward the large intestine.
The main regions of the large intestine are the cecum, the colon, and the rectum. The large intestine absorbs water and forms feces, and is responsible for defecation. Bacterial flora break down additional carbohydrate residue, and synthesize certain vitamins. The mucosa of the large intestinal wall is generously endowed with goblet cells, which secrete mucus that eases the passage of feces. The entry of feces into the rectum activates the defecation reflex.
Review Questions
Q. Which part of the alimentary canal is retroperitoneal?
A. stomach
B. proximal small intestine
C. distal small intestine
D. transverse colon
- Answer
-
B
Q. Which of these are found inside villi?
A. haustra
B. lacteals
C. bacterial flora
D. intestinal glands
- Answer
-
B
Q. What section of the alimentary canal has the greatest amount of MALT?”
A. stomach
B. duodenum
C. cecum
D. ileum
- Answer
-
D
Q. Which part of the large intestine attaches to the appendix?
A. cecum
B. ascending colon
C. transverse colon
D. descending colon
- Answer
-
A
Critical Thinking Questions
Q. Why should there be capillaries inside villi?
- Answer
-
A. Water soluble nutrients from the breakdown of carbohydrates and proteins are absorbed through a capillary bed in the villi of the small intestine. Lipid breakdown products are absorbed into a lacteal in the villi, and transported via the lymphatic system to the bloodstream.
Q. Should a person, with the colon removed, worry about becoming malnourished? Why or why not?
- Answer
-
A. No, the colon absorbs very little nutrients; it does absorb water. Without the colon, the content leaving the small intestine will contain more fluid than normal feces.
Q. Describe some differences between the walls of the large and small intestines.
- Answer
-
A. The mucosa of the small intestine includes circular folds, villi, and microvilli. The wall of the large intestine has a thick mucosal layer, and deeper and more abundant mucus-secreting glands that facilitate the smooth passage of feces. There are three features that are unique to the large intestine: teniae coli, haustra, and epiploic appendages.
References
American Cancer Society (US). Cancer facts and figures: colorectal cancer: 2011–2013 [Internet]. c2013 [cited 2013 Apr 3]. Available from: http://www.cancer.org/Research/CancerFactsFigures/ColorectalCancerFactsFigures/colorectal-cancer-facts-figures-2011-2013-page .
The Nutrition Source. Fiber and colon cancer: following the scientific trail [Internet]. Boston (MA): Harvard School of Public Health; c2012 [cited 2013 Apr 3]. Available from:www.hsph.harvard.edu/nutritio...cer/index.html.
Centers for Disease Control and Prevention (US). Morbidity and mortality weekly report: notifiable diseases and mortality tables [Internet]. Atlanta (GA); [cited 2013 Apr 3]. Available from: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6101md.htm?s_cid=mm6101md_w .
Glossary
- anal canal
- final segment of the large intestine
- anal column
- long fold of mucosa in the anal canal
- anal sinus
- recess between anal columns
- appendix
- (vermiform appendix) coiled tube attached to the cecum
- ascending colon
- first region of the colon
- bacterial flora
- bacteria in the large intestine
- brush border
- fuzzy appearance of the small intestinal mucosa created by microvilli
- cecum
- pouch forming the beginning of the large intestine
- circular fold
- (also, plica circulare) deep fold in the mucosa and submucosa of the small intestine
- colon
- part of the large intestine between the cecum and the rectum
- descending colon
- part of the colon between the transverse colon and the sigmoid colon
- duodenal gland
- (also, Brunner’s gland) mucous-secreting gland in the duodenal submucosa
- duodenum
- first part of the small intestine, which starts at the pyloric sphincter and ends at the jejunum
- epiploic appendage
- small sac of fat-filled visceral peritoneum attached to teniae coli
- external anal sphincter
- voluntary skeletal muscle sphincter in the anal canal
- feces
- semisolid waste product of digestion
- flatus
- gas in the intestine
- gastrocolic reflex
- propulsive movement in the colon activated by the presence of food in the stomach
- gastroileal reflex
- long reflex that increases the strength of segmentation in the ileum
- haustrum
- small pouch in the colon created by tonic contractions of teniae coli
- haustral contraction
- slow segmentation in the large intestine
- hepatopancreatic ampulla
- (also, ampulla of Vater) bulb-like point in the wall of the duodenum where the bile duct and main pancreatic duct unite
- hepatopancreatic sphincter
- (also, sphincter of Oddi) sphincter regulating the flow of bile and pancreatic juice into the duodenum
- ileocecal sphincter
- sphincter located where the small intestine joins with the large intestine
- ileum
- end of the small intestine between the jejunum and the large intestine
- internal anal sphincter
- involuntary smooth muscle sphincter in the anal canal
- intestinal gland
- (also, crypt of Lieberkühn) gland in the small intestinal mucosa that secretes intestinal juice
- intestinal juice
- mixture of water and mucus that helps absorb nutrients from chyme
- jejunum
- middle part of the small intestine between the duodenum and the ileum
- lacteal
- lymphatic capillary in the villi
- large intestine
- terminal portion of the alimentary canal
- left colic flexure
- (also, splenic flexure) point where the transverse colon curves below the inferior end of the spleen
- main pancreatic duct
- (also, duct of Wirsung) duct through which pancreatic juice drains from the pancreas
- major duodenal papilla
- point at which the hepatopancreatic ampulla opens into the duodenum
- mass movement
- long, slow, peristaltic wave in the large intestine
- mesoappendix
- mesentery of the appendix
- microvillus
- small projection of the plasma membrane of the absorptive cells of the small intestinal mucosa
- migrating motility complex
- form of peristalsis in the small intestine
- motilin
- hormone that initiates migrating motility complexes
- pectinate line
- horizontal line that runs like a ring, perpendicular to the inferior margins of the anal sinuses
- rectal valve
- one of three transverse folds in the rectum where feces is separated from flatus
- rectum
- part of the large intestine between the sigmoid colon and anal canal
- right colic flexure
- (also, hepatic flexure) point, at the inferior surface of the liver, where the ascending colon turns abruptly to the left
- saccharolytic fermentation
- anaerobic decomposition of carbohydrates
- sigmoid colon
- end portion of the colon, which terminates at the rectum
- small intestine
- section of the alimentary canal where most digestion and absorption occurs
- tenia coli
- one of three smooth muscle bands that make up the longitudinal muscle layer of the muscularis in all of the large intestine except the terminal end
- transverse colon
- part of the colon between the ascending colon and the descending colon
- Valsalva’s maneuver
- voluntary contraction of the diaphragm and abdominal wall muscles and closing of the glottis, which increases intra-abdominal pressure and facilitates defecation
- villus
- projection of the mucosa of the small intestine
Contributors and Attributions
-
OpenStax Anatomy & Physiology (CC BY 4.0). Access for free at https://openstax.org/books/anatomy-and-physiology


8.4: The Seven Steps of the Research Process
The following seven steps outline a simple and effective strategy for finding information for a research paper and documenting the sources you find. Depending on your topic and your familiarity with the library, you may need to rearrange or recycle these steps. Adapt this outline to your needs. We are ready to help you at every step in your research.
STEP 1: IDENTIFY AND DEVELOP YOUR TOPIC
SUMMARY: State your topic as a question. For example, if you are interested in finding out about use of alcoholic beverages by college students, you might pose the question, “What effect does use of alcoholic beverages have on the health of college students?” Identify the main concepts or keywords in your question.
More details on how to identify and develop your topic.
STEP 2: FIND BACKGROUND INFORMATION
SUMMARY: Look up your keywords in the indexes to subject encyclopedias. Read articles in these encyclopedias to set the context for your research. Note any relevant items in the bibliographies at the end of the encyclopedia articles. Additional background information may be found in your lecture notes, textbooks, and reserve readings.
More suggestions on how to find background information.
STEP 3: USE CATALOGS TO FIND BOOKS AND MEDIA
SUMMARY: Use guided keyword searching to find materials by topic or subject. Print or write down the citation (author, title,etc.) and the location information (call number and library). Note the circulation status. When you pull the book from the shelf, scan the bibliography for additional sources. Watch for book-length bibliographies and annual reviews on your subject; they list citations to hundreds of books and articles in one subject area. Check the standard subject subheading “—BIBLIOGRAPHIES,” or titles beginning with Annual Review of… in the Cornell Library Classic Catalog.
More detailed instructions for using catalogs to find books.
Finding media (audio and video) titles.
STEP 4: USE INDEXES TO FIND PERIODICAL ARTICLES
SUMMARY: Use periodical indexes and abstracts to find citations to articles. The indexes and abstracts may be in print or computer-based formats or both. Choose the indexes and format best suited to your particular topic; ask at the reference desk if you need help figuring out which index and format will be best. You can find periodical articles by the article author, title, or keyword by using the periodical indexes in theLibrary home page. If the full text is not linked in the index you are using, write down the citation from the index and search for the title of the periodical in the Cornell Library Classic Catalog. The catalog lists the print, microform, and electronic versions of periodicals at Cornell.
How to find and use periodical indexes at Cornell.
STEP 5: FIND INTERNET RESOURCES
SUMMARY: Use search engines. Check to see if your class has a bibliography or research guide created by librarians.
Finding Information on the Internet : A thorough tutorial from UC Berkeley.
STEP 6: EVALUATE WHAT YOU FIND
SUMMARY: See How to Critically Analyze Information Sources and Distinguishing Scholarly from Non-Scholarly Periodicals: A Checklist of Criteria for suggestions on evaluating the authority and quality of the books and articles you located.
If you have found too many or too few sources, you may need to narrow or broaden your topic. Check with a reference librarian or your instructor. When you’re ready to write, here is an annotated list of books to help you organize, format, and write your paper.

Citing or documenting the sources used in your research serves two purposes, it gives proper credit to the authors of the materials used, and it allows those who are reading your work to duplicate your research and locate the sources that you have listed as references.
Knowingly representing the work of others as your own is plagarism. (See Cornell’s Code of Academic Integrity ). Use one of the styles listed below or another style approved by your instructor. Handouts summarizing the APA and MLA styles are available at Uris and Olin Reference.
Available online :
RefWorks is a web-based program that allows you to easily collect, manage, and organize bibliographic references by interfacing with databases. RefWorks also interfaces directly with Word, making it easy to import references and incorporate them into your writing, properly formatted according to the style of your choice.
See our guide to citation tools and styles.
Format the citations in your bibliography using examples from the following Library help pages: Modern Language Association (MLA) examples and American Psychological Association (APA) examples .
- Style guides in print (book) format:
- MLA Handbook for Writers of Research Papers . 7th ed. New York: MLA, 2009. This handbook is based on the MLA Style Manual and is intended as an aid for college students writing research papers. Included here is information on selecting a topic, researching the topic, note taking, the writing of footnotes and bibliographies, as well as sample pages of a research paper. Useful for the beginning researcher.
- Publication Manual of the American Psychological Association . 6th ed. Washington: APA, 2010. The authoritative style manual for anyone writing in the field of psychology. Useful for the social sciences generally. Chapters discuss the content and organization of a manuscript, writing style, the American Psychological Association citation style, and typing, mailing and proofreading.
If you are writing an annotated bibliography, see How to Prepare an Annotated Bibliography.
RESEARCH TIPS:
- WORK FROM THE GENERAL TO THE SPECIFIC. Find background information first, then use more specific and recent sources.
 Record the complete citation for each source you find; you may need it again later.
 Check your topic words against a thesaurus or subject heading list.
Contributors and Attributions
- The Seven Steps. Provided by : Research & Learning Services Olin Library Cornell University Library Ithaca, NY, USA. Located at : http://guides.library.cornell.edu/sevensteps . License : CC BY-NC-SA: Attribution-NonCommercial-ShareAlike . License Terms : Lumen Learning has received permission from Olin & Uris Libraries to reproduce this and adapt it for our own use
- Research Minutes: How to Identify Scholarly Journal Articles. Authored by : Olin & Uris Libraries, Cornell University. Located at : https://youtu.be/uDGJ2CYfY9A . License : All Rights Reserved . License Terms : Standard YouTube License
- Research Minutes: How to Read Citations. Authored by : Olin & Uris Libraries, Cornell University. Located at : https://youtu.be/R1yNDvmjqaE . License : All Rights Reserved . License Terms : Standard YouTube License
- Research Minutes: How to Identify Substantive News Articles. Authored by : Olin & Uris Libraries, Cornell University. Located at : https://youtu.be/QAiJL5B5esM . License : All Rights Reserved . License Terms : Standard YouTube License


3.9: End of Chapter
REFERENCES
Introductory quote: A. Sommerfeld, Natumissenschaftliche Rundschau , Volume 1, pages 97-100 , reprinted in Gesammelte Schriften (Vieweg, Braunschweig, 1968), Volume IV, pages 640-643.
Galileo quote, Section 3.1: Galileo Galilei, Dialogue Concerning the Two Chief World Systems - Ptolemaic and Copernican , first published February 1632; the translation quoted here is by Stillman Drake (University of California Press, Berkeley, 1962), pages 186ff. Galileo’s writings, along with those of Dante, by reason of their strength and aptness, are treasures of human thought, studied today in Italy by secondary school students as part of a great literary heritage.
Einstein quote, Box 3-1: Albert Einstein, "On the Electrodynamics of Moving Bodies," Annalen der Physik , Volume 17, pages 891-921 (1905), translated by Arthur I. Miller in Albert Einstein’s Special Theory of Relativity (AddisonWesley, Reading, Mass., 1981), page 392.
ACKNOWLEDGMENTS
The idea for Box 3-1 was suggested by Kenneth L. Laws. Box 3-4 and the argument for Section 3.6, Invariance of Transverse Dimension, is adapted from material by William A. Shurcliff, private communications. Sample Problem 3-2 is adapted from A. P. French, Special Relativity (W. W. Norton, New York, 1968), page 121,


5.13: Gramática. El verbo Ir + a + infinitivo
-
- Last updated
- Save as PDF
- Erica Brown, Alejandra Escudero, María Cristina Montoya, & Elizabeth Small
- SUNY Oneonta via OER SUNY
Objetivos
- Recognize statements about plans and future events which use the infinitive after ir + a
The verb ir is used as a way to describe future plans when used in the following manner: ir + a + infinitive. It’s important to remember that you only need to conjugate ir in this kind of sentence. Another way of looking at it is the rule that after a preposition (like a ), a verb will always be in the infinitive.
- Yo voy a estudiar esta noche. ( I’m going to study tonight. )
- Tú no vas a ganar mucho dinero aquí. ( You are not going to earn much money here. )
- Ella no va a comprar el libro. ( She’s not going to buy the book. )
- Ustedes van a mirar la tele, ¿verdad? (Y ou all are going to watch TV, right? )
Vocabulario útil para hablar del futuro
- Esta tarde ( this afternoon )
- Esta noche ( tonight )
- Esta semana (t his week )
- Este año ( this year )
- Mañana ( tomorrow )
- Pasado mañana ( the day after tomorrow )
- La semana que viene ( next week )
- El próximo año ( next year )
Contributors and Attributions
- Prairie Dog. Located at : https://www.pexels.com/photo/eating-animal-carrot-prairie-dog-4245/ . License : Public Domain: No Known Copyright
- Gramática: Ir + a + infinitivo. Authored by : SUNY Oneonta with Lumen Learning. Provided by : SUNY Oneonta. License : CC BY: Attribution


32.5: Pollination and Fertilization - Pollination by Insects
- Explain how pollination by insects aids plant reproduction
Bees
Bees are perhaps the most important pollinator of many garden plants and most commercial fruit trees. The most common species of bees are bumblebees and honeybees. Since bees cannot see the color red, bee-pollinated flowers usually have shades of blue, yellow, or other colors. Bees collect energy -rich pollen or nectar for their survival and energy needs. They visit flowers that are open during the day, are brightly colored, have a strong aroma or scent, and have a tubular shape, typically with the presence of a nectar guide. A nectar guide includes regions on the flower petals that are visible only to bees, which help guide bees to the center of the flower, thus making the pollination process more efficient. The pollen sticks to the bees’ fuzzy hair; when the bee visits another flower, some of the pollen is transferred to the second flower. Recently, there have been many reports about the declining population of honeybees. Many flowers will remain unpollinated, failing to bear seeds if honeybees disappear. The impact on commercial fruit growers could be devastating.
Flies
Many flies are attracted to flowers that have a decaying smell or an odor of rotting flesh. These flowers, which produce nectar, usually have dull colors, such as brown or purple. They are found on the corpse flower or voodoo lily ( Amorphophallus ), dragon arum ( Dracunculus ), and carrion flower (Stapleia, Rafflesia ). The nectar provides energy while the pollen provides protein. Wasps are also important insect pollinators, pollinating many species of figs.
Butterflies and Moths
Butterflies, such as the monarch, pollinate many garden flowers and wildflowers, which are usually found in clusters. These flowers are brightly colored, have a strong fragrance, are open during the day, and have nectar guides. The pollen is picked up and carried on the butterfly’s limbs. Moths, on the other hand, pollinate flowers during the late afternoon and night. The flowers pollinated by moths are pale or white and are flat, enabling the moths to land. One well-studied example of a moth-pollinated plant is the yucca plant, which is pollinated by the yucca moth. The shape of the flower and moth have adapted in a way to allow successful pollination. The moth deposits pollen on the sticky stigma for fertilization to occur later. The female moth also deposits eggs into the ovary. As the eggs develop into larvae, they obtain food from the flower and developing seeds. Thus, both the insect and flower benefit from each other in this symbiotic relationship. The corn earworm moth and Gaura plant have a similar relationship.
Key Points
- Adaptations such as bright colors, strong fragrances, special shapes, and nectar guides are used to attract suitable pollinators.
- Important insect pollinators include bees, flies, wasps, butterflies, and moths.
- Bees and butterflies are attracted to brightly-colored flowers that have a strong scent and are open during the day, whereas moths are attracted to white flowers that are open at night.
- Flies are attracted to dull brown and purple flowers that have an odor of decaying meat.
- Nectar guides, which are only visible to certain insects, facilitate pollination by guiding bees to the pollen at the center of flowers.
- Insects and flowers both benefit from their specialized symbiotic relationships; plants are pollinated while insects obtain valuable sources of food.
Key Terms
- nectar guide : markings or patterns seen in flowers of some angiosperm species that guide pollinators to nectar or pollen


8.3: Body Mass Index
What is BMI?
BMI is a person’s weight in kilograms divided by the square of height in meters. BMI does not measure body fat directly, but research has shown that BMI is moderately correlated with more direct measures of body fat obtained from skinfold thickness measurements, bioelectrical impedance, densitometry (underwater weighing), dual energy x-ray absorptiometry (DXA) and other methods. Furthermore, BMI appears to be as strongly correlated with various metabolic and disease outcome as are these more direct measures of body fatness. In general, BMI is an inexpensive and easy-to-perform method of screening for weight category, for example underweight, normal or healthy weight, overweight, and obesity.
How is BMI used?
A high BMI can be an indicator of high body fatness. BMI can be used as a screening tool but is not diagnostic of the body fatness or health of an individual.
To determine if a high BMI is a health risk, a healthcare provider would need to perform further assessments. These assessments might include skinfold thickness measurements, evaluations of diet, physical activity, family history, and other appropriate health screenings.
What are the BMI trends for adults in the United States?
The prevalence of adult BMI greater than or equal to 30 kg/m 2 (obese status) has greatly increased since the 1970s. Recently, however, this trend has leveled off, except for older women. Obesity has continued to increase in adult women who are age 60 years and older.
Prevalence of Self-Reported Obesity Among U.S. Adults by State and Territory, BRFSS, 2016
Why is BMI used to measure overweight and obesity?
BMI can be used for population assessment of overweight and obesity. Because calculation requires only height and weight, it is inexpensive and easy to use for clinicians and for the general public. BMI can be used as a screening tool for body fatness but is not diagnostic.
To see the formula based on either kilograms and meters or pounds and inches, visit How is BMI calculated?
What are some of the other ways to assess excess body fatness besides BMI?
Other methods to measure body fatness include skinfold thickness measurements (with calipers), underwater weighing, bioelectrical impedance, dual-energy x-ray absorptiometry (DXA), and isotope dilution 1,2,3 . However, these methods are not always readily available, and they are either expensive or need to be conducted by highly trained personnel. Furthermore, many of these methods can be difficult to standardize across observers or machines, complicating comparisons across studies and time periods.
How is BMI interpreted for adults?
For adults 20 years old and older, BMI is interpreted using standard weight status categories. These categories are the same for men and women of all body types and ages.
The standard weight status categories associated with BMI ranges for adults are shown in the following table.
| BMI | Weight Status |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Normal or Healthy Weight |
| 25.0 – 29.9 | Overweight |
| 30.0 and Above | Obese |
For example, here are the weight ranges, the corresponding BMI ranges, and the weight status categories for a person who is 5′ 9″.
| Height | Weight Range | BMI | Weight Status |
|---|---|---|---|
| 5′ 9″ | 124 lbs or less | Below 18.5 | Underweight |
| 125 lbs to 168 lbs | 18.5 to 24.9 | Normal or Healthy Weight | |
| 169 lbs to 202 lbs | 25.0 to 29.9 | Overweight | |
| 203 lbs or more | 30 or higher | Obese |
For children and teens, the interpretation of BMI depends upon age and sex.
For adults, the interpretation of BMI does not depend on sex or age.
How good is BMI as an indicator of body fatness?
The correlation between the BMI and body fatness is fairly strong, but even if 2 people have the same BMI, their level of body fatness may differ.
In general:
- At the same BMI, women tend to have more body fat than men.

The accuracy of BMI as an indicator of body fatness also appears to be higher in persons with higher levels of BMI and body fatness. While, a person with a very high BMI (e.g., 35 kg/m 2 ) is very likely to have high body fat, a relatively high BMI can be the results of either high body fat or high lean body mass (muscle and bone). A trained healthcare provider should perform appropriate health assessments in order to evaluate an individual’s health status and risks.
If an athlete or other person with a lot of muscle has a BMI over 25, is that person still considered to be overweight?
According to the BMI weight status categories, anyone with a BMI between 25 and 29.9 would be classified as overweight and anyone with a BMI over 30 would be classified as obese.
However, athletes may have a high BMI because of increased muscularity rather than increased body fatness. In general, a person who has a high BMI is likely to have body fatness and would be considered to be overweight or obese, but this may not apply to athletes. A trained healthcare provider should perform appropriate health assessments in order to evaluate an individual’s health status and risks.
- Body Mass Index. Authored by : Centers for Disease Control and Prevention. Provided by : U.S. Department of Health and Human Services. Located at : https://www.cdc.gov/healthyweight/assessing/bmi/adult_bmi/index.html . License : Public Domain: No Known Copyright
- Map: Prevalence of Self-Reported Obesity Among U.S. Adults by State and Territory. Authored by : Centers for Disease Control and Prevention. Located at : https://www.cdc.gov/obesity/data/prevalence-maps.html . License : Public Domain: No Known Copyright


5.8: Current and Resistance (Summary)
Key Terms
| ampere (amp) | SI unit for current; \(\displaystyle 1A=1C/s\) |
| circuit | complete path that an electrical current travels along |
| conventional current | current that flows through a circuit from the positive terminal of a battery through the circuit to the negative terminal of the battery |
| current density | flow of charge through a cross-sectional area divided by the area |
| diode | nonohmic circuit device that allows current flow in only one direction |
| drift velocity | velocity of a charge as it moves nearly randomly through a conductor, experiencing multiple collisions, averaged over a length of a conductor, whose magnitude is the length of conductor traveled divided by the time it takes for the charges to travel the length |
| electrical conductivity | measure of a material’s ability to conduct or transmit electricity |
| electrical current | rate at which charge flows, \(\displaystyle I=\frac{dQ}{dt}\) |
| electrical power | time rate of change of energy in an electric circuit |
| nonohmic | type of a material for which Ohm’s law is not valid |
| ohm | (\(\displaystyle Ω\)) unit of electrical resistance, \(\displaystyle 1Ω=1V/A\) |
| ohmic | type of a material for which Ohm’s law is valid, that is, the voltage drop across the device is equal to the current times the resistance |
| Ohm’s law | empirical relation stating that the current I is proportional to the potential difference V; it is often written as \(\displaystyle V=IR\), where R is the resistance |
| resistance | electric property that impedes current; for ohmic materials, it is the ratio of voltage to current, \(\displaystyle R=V/I\) |
| resistivity | intrinsic property of a material, independent of its shape or size, directly proportional to the resistance, denoted by \(\displaystyle ρ\) |
| schematic | graphical representation of a circuit using standardized symbols for components and solid lines for the wire connecting the components |
Key Equations
| Average electrical current | \(\displaystyle I_{ave}=\frac{ΔQ}{Δt}\) |
| Definition of an ampere | \(\displaystyle 1A=1C/s\) |
| Electrical current | \(\displaystyle I=\frac{dQ}{dt}\) |
| Drift velocity | \(\displaystyle v_d=\frac{I}{nqA}\) |
| Current density | \(\displaystyle I=∬_{area}\vec{J}⋅d\vec{A}\) |
| Resistivity | \(\displaystyle ρ=\frac{E}{J}\) |
| Common expression of Ohm’s law | \(\displaystyle V=IR\) |
| Resistivity as a function of temperature | \(\displaystyle ρ=ρ_0[1+α(T−T_0)]\) |
| Definition of resistance | \(\displaystyle R≡\frac{V}{I}\) |
| Resistance of a cylinder of material | \(\displaystyle R=ρ\frac{L}{A}\) |
| Temperature dependence of resistance | \(\displaystyle R=R_0(1+αΔT)\) |
| Electric power | \(\displaystyle P=IV\) |
| Power dissipated by a resistor | \(\displaystyle P=I^2R=\frac{V^2}{R}\) |
Summary
Electrical Current
- The average electrical current \(\displaystyle I_{ave}\) is the rate at which charge flows, given by \(\displaystyle I_{ave}=\frac{ΔQ}{Δt}\), where \(\displaystyle ΔQ\) is the amount of charge passing through an area in time \(\displaystyle Δt\).
- The instantaneous electrical current, or simply the current I, is the rate at which charge flows. Taking the limit as the change in time approaches zero, we have \(\displaystyle I=\frac{dQ}{dt}\), where \(\displaystyle \frac{dQ}{dt}\) is the time derivative of the charge.
- The direction of conventional current is taken as the direction in which positive charge moves. In a simple direct-current (DC) circuit, this will be from the positive terminal of the battery to the negative terminal.
- The SI unit for current is the ampere, or simply the amp (A), where \(\displaystyle 1A=1C/s\).
- Current consists of the flow of free charges, such as electrons, protons, and ions.
Basic Model of Conduction in Metals
- The current through a conductor depends mainly on the motion of free electrons.
- When an electrical field is applied to a conductor, the free electrons in a conductor do not move through a conductor at a constant speed and direction; instead, the motion is almost random due to collisions with atoms and other free electrons.
- Even though the electrons move in a nearly random fashion, when an electrical field is applied to the conductor, the overall velocity of the electrons can be defined in terms of a drift velocity.
- The current density is a vector quantity defined as the current through an infinitesimal area divided by the area.
- The current can be found from the current density, \(\displaystyle I=∬_{area}\vec{J}⋅d\vec{A}\).
- An incandescent light bulb is a filament of wire enclosed in a glass bulb that is partially evacuated. Current runs through the filament, where the electrical energy is converted to light and heat.
Resistivity and Resistance
- Resistance has units of ohms (\(\displaystyle Ω\)), related to volts and amperes by \(\displaystyle 1Ω=1V/A\).
- The resistance R of a cylinder of length L and cross-sectional area A is \(\displaystyle R=\frac{ρL}{A}\), where \(\displaystyle ρ\) is the resistivity of the material.
- Values of \(\displaystyle ρ\) in Table 9.1 show that materials fall into three groups—conductors, semiconductors, and insulators.
- Temperature affects resistivity; for relatively small temperature changes \(\displaystyle ΔT\), resistivity is \(\displaystyle ρ=ρ_0(1+αΔT)\), where \(\displaystyle ρ_0\) is the original resistivity and \(\displaystyle α\) is the temperature coefficient of resistivity.
- The resistance R of an object also varies with temperature: \(\displaystyle R=R_0(1+αΔT)\), where \(\displaystyle R_0\) is the original resistance, and R is the resistance after the temperature change.
Ohm's Law
- Ohm’s law is an empirical relationship for current, voltage, and resistance for some common types of circuit elements, including resistors. It does not apply to other devices, such as diodes.
- One statement of Ohm’s law gives the relationship among current I, voltage V, and resistance R in a simple circuit as \(\displaystyle V=IR\).
- Another statement of Ohm’s law, on a microscopic level, is \(\displaystyle J=σE\).
Electrical Energy and Power
- Electric power is the rate at which electric energy is supplied to a circuit or consumed by a load.
- Power dissipated by a resistor depends on the square of the current through the resistor and is equal to \(\displaystyle P=I^2R=\frac{V^2}{R}\).
- The SI unit for electric power is the watt and the SI unit for electric energy is the joule. Another common unit for electric energy, used by power companies, is the kilowatt-hour (kW ⋅· h).
- The total energy used over a time interval can be found by \(\displaystyle E=∫Pdt\).
Contributors and Attributions
Samuel J. Ling (Truman State University), Jeff Sanny (Loyola Marymount University), and Bill Moebs with many contributing authors. This work is licensed by OpenStax University Physics under a
Creative Commons Attribution License (by 4.0)
.


26.5: Older Adult Health
By the end of this section, you should be able to:
- Recognize major diseases affecting older adults.
- Examine major risk factors influencing the health of older adults.
- Create educational interventions to promote self-care for health promotion, illness prevention, and illness management of older adults.
- Identify Healthy People 2030 goals established for older adults.
- Describe health promotion and disease prevention actions designed to improve the health of older adults.
- Discuss strategies for integrating sociocultural and linguistically responsive health promotion and disease prevention interventions in clinical practice of older adults.
Thanks to advances in technology, improvements in health care services, interventions in public health, and research on the utilization of health services, people are living longer and healthier lives. Much improvement lies in reducing infectious diseases, which were major killers at the turn of the 20th century. U.S. life expectancy increased from 48.3 years for women and 46.3 years for men in 1900 to 79.3 years and 74.1 years, respectively, in 2000. In 2019, Americans’ life expectancy at birth was 81.4 years for women and 76.3 years for men (NCHS, 2023a). Since 2020, however, drops in life expectancy have occurred in the United States. In 2020, life expectancy at birth for women was 79.9 years and dropped further to 79.1 years in 2021. In 2020, life expectancy at birth for men was 74.2 years and dropped to 73.2 years in 2021 (NCHS, 2022b). These declines are largely due to the COVID-19 pandemic and drug overdose (NCHS, 2022b). Despite this decrease, the country will see continued growth in the older adult population, comprising those aged 65 and over. In 2030, the projected population will be more than twice as large as it was in 2000, growing from 35 million to 73 million and representing 21 percent of the total U.S. population (Federal Interagency Forum on Aging-Related Statistics, 2020). Also of note, nearly one in four older adults in 2019 were members of racial or ethnic minority populations (Administration on Aging, 2021).
As this group lives longer, society must meet their needs. The NCHS (2023d) reported that in 2021, 22.6 percent of noninstitutionalized persons aged 65 and over were in fair or poor health. In 2019, 16.6 percent of people aged 65 and over had one or more hospital stays. According to the American Health Care Association and the National Center for Assisted Living (AHCA/NCAL, 2023), more than 800,000 Americans reside in assisted living communities. The Administration on Aging (2021) indicated that in 2019, only 1.2 million persons (1 percent of persons aged 65–74, 2 percent aged 75–84, and 8 percent aged 85 and over) lived in nursing homes. In 2022, 20.5 percent of men and 26.7 percent of women aged 65 to 74 lived alone, and 23.8 percent of men and 42.5 percent of women aged 75 and over lived alone (U.S. Census Bureau, 2022). Mechanisms of providing health insurance , supportive environments, healthy communities, and social safety nets , including health care provision, must be in place. Health promotion and disease prevention are essential parts of maintaining the older adult population’s health and well-being. Older adults must stay informed about healthy lifestyle choices and work with nurses and other health care professionals to create personalized plans for maintaining good health (Figure 26.6).
Major Diseases Affecting Older Adults
A variety of diseases affect older adults.
- Heart disease, cancer, and COVID-19 were the leading causes of death among persons ages 65 and over in the United States in 2021.
-
Obesity
remains an issue for this population.
- 41.9 percent of noninstitutionalized men aged 65 to 74 in 2015–2018
- 31.8 percent of noninstitutionalized men aged 75 and over in 2015–2018
- 45.9 percent of noninstitutionalized women aged 65 to 74 in 2015–2018
- 36.1 percent of noninstitutionalized women aged 75 and over in 2015–2018
-
Hypertension
is an even larger issue.
- 66.7 percent of men aged 65 to 74 in 2015–2018
- 81.5 percent of men aged 75 and over in 2015–2018
- 74.3 percent of women aged 65 to 74 in 2015–2018
- 86 percent of women aged 75 and older in 2015–2018 (NCHS, 2023d)
In 2019, leading chronic conditions for noninstitutionalized older adults included (Administration on Aging, 2021):
- arthritis (48 percent);
- physician-diagnosed and undiagnosed diabetes (29 percent in 2015–2018);
- any cancer (25 percent);
- coronary heart disease (14 percent);
- COPD, emphysema, or chronic bronchitis (10 percent);
- myocardial infarction (9 percent);
- stroke (9 percent in 2017–2018); and
- angina (4 percent).
According to the Federal Interagency Forum on Aging-Related Statistics (2020), in 2015, 7.4 percent of older adult men and 7.5 percent of older adult women not living in nursing homes had dementia .
Arthritis affects about one in every four adults in the United States. Its prevalence increases with age, and it is more common in women than in men, more common among adults with fair/poor health compared to those with excellent/very good health, and less common among adults who meet physical activity recommendations compared to those who are insufficiently active or inactive (CDC, 2021l). The prevalence of this disease is expected to increase, with projections indicating that an estimated 78.4 million adults will have been diagnosed with arthritis by 2040 (Figure 26.7) (CDC, 2021l). U.S. adults with arthritis are more likely to be obese or have diabetes or heart disease than those who do not have arthritis. For instance, 28.8 percent of adults who had arthritis in 2016–2018 were also obese, 47 percent of adults who had arthritis in 2013–2015 also had diabetes, and 49 percent of adults who had arthritis in 2013–2015 also had heart disease (CDC, 2022k).
While coronary heart disease and stroke were common in the adult population, diseases of the heart and circulatory vessels are also prevalent in the growing population of older adults. As people age, managing these diseases becomes more difficult for older adults with comorbidities related to cognition, sleep, physical balance, and strength factors (CDC, 2019a). Myocardial infarction, or a heart attack, occurs when the flow of oxygen-rich blood to a section of heart muscle becomes blocked, leading to a lack of oxygen, which may damage the heart muscle. Angina, a symptom of CAD, is chest pain or discomfort resulting from an area of heart muscle becoming starved of oxygen-rich blood (CDC, 2019a). The prevalence of coronary heart disease in 2019 was 11.4 percent of White people, 10 percent of Black people, 8.8 percent of Hispanic people, and 6.3 percent of Asians and Pacific Islanders. Prevalence was 16.5 percent for those with no high school diploma and 10.9 percent for those with some college or more.
Risk Factors Influencing the Health of Older Adults
The Federal Interagency Forum on Aging-Related Statistics (2020) considers the following six indicators as health behavior risks: lack of vaccinations, lack of colorectal cancer screenings, poor diet, physical inactivity, obesity, and cigarette smoking. In 2018, about 69 percent of older adults reported receiving an influenza vaccine in the past 12 months. This included 72 percent of non-Hispanic White people compared with only 60.4 percent of non-Hispanic Black people and 63 percent of Hispanic people. The percentage of people aged 50 to 75 who received colorectal cancer screenings increased over the last 8 years. Older adults completing the Healthy Eating Index—2015 had their highest component scores in Whole Fruits, Total Protein Foods, and Seafood and Plant Proteins. Their overall diet quality was 64 out of 100. In 2018, only 14 percent of older adults participated in leisure-time physical activity that met the Physical Activity Guidelines for Americans. The percentage of older adults with obesity increased from 22 percent in 1988–1994 to 30 percent in 2003–2006 and 40 percent in 2015–2018. Finally, the percentage of older adults who were current cigarette smokers has declined, as in 2018, 10 percent of older adult men and 7 percent of older adult women were current smokers (Federal Interagency Forum on Aging-Related Statistics, 2020).
Polypharmacy , the use of five or more medications, is another risk factor that impacts the health of older adults (WHO, 2019). As the population ages, people are more likely to experience comorbidities that require multiple medications. Older adults are at risk for adverse drug events (ADE) and drug interactions between these multiple medications. The most common ADE in older adults is impaired mobility, which can lead to falls, injuries, or death. Older adults are especially vulnerable due to age-related physiologic changes resulting from the absorption, distribution, metabolism, and elimination of drugs. Polypharmacy, in addition to frailty or any other condition that impacts mobility, markedly increases the risk of mortality (Parulekar & Rogers, 2018).
Sensory loss issues are another important risk factor for older adults. Hearing, vision, and touch can affect one’s enjoyment of activities and ability to communicate and stay involved with others (MedlinePlus, 2022). Sensory loss issues can also put the older adult at risk for falls, which can lead to injuries or death. Age-related changes in the ear can lead to balance difficulties. Reduced vision may also lead to injuries, and perception related to touch may be impaired, causing difficulties walking related to a reduced ability to perceive where the body is in relation to the floor (Medline Plus, 2022). Other difficulties related to touch include a reduced ability to detect pressure, which can lead to pressure ulcers, and a reduced sensitivity to pain, including temperature, which could lead to burns.
A fall risk assessment may benefit older adults in the population health setting. The assessment typically includes an initial screening with questions about overall health, history of previous falls, and current issues with balance, standing, and/or walking. It should also include a set of tasks or fall assessment tools to test the older adult’s strength, balance, and gait (MedlinePlus, 2021). One common approach to fall assessment is the use of the CDC’s (2021i) Stopping Elderly Accidents, Deaths, and Injuries (STEADI) approach. STEADI provides screening, assessment, and intervention guidelines. Particular assessments included in STEADI are:
- Timed Up-and-Go (Tug) test to assess gait,
- 30-Second Chair Stand test to assess strength and balance, and
- 4-Stage Balance test to assess balance.
STEADI Resource Algorithm assessment results illustrate the degree to which an older adult is at risk of falling and may indicate areas (gait, strength, and/or balance) to address.
Ageism , discrimination against older people because of negative and inaccurate stereotyping, is a risk factor for the mental heath of older adults (Weir, 2023). It is so deeply rooted in American societies that it is largely ignored. The negative effects of ageism on older adults’ physical and mental well-being include:
- earlier death;
- poorer physical health, affecting sexual/reproductive health and the ability to recover from disabiity;
- increased risky health behaviors;
- poorer mental health, including the onset of depression, increases in depressive symptoms over time, and lifetime depression; and
- lower quality of life, social isolation, and loneliness (WHO, 2023a).
Educational Interventions to Promote Self-Care in Older Adults
Self-care is crucial for the well-being of older adults. Aging-related physical and cognitive changes can make it more difficult to take care of oneself. However, practicing self-care can help older adults maintain their independence, prevent or manage health problems, and improve their overall quality of life (Marques et al., 2019). Exercise, healthy eating, and proper medication management can help older adults maintain their physical health. Regular physical activity can help prevent chronic diseases, while a healthy diet can provide the nutrients needed to support overall health. Meditation , socializing, and hobbies can promote mental well-being and reduce the risk of depression and anxiety. Participating in social activities or volunteering can increase social engagement and reduce feelings of isolation or loneliness. Older adults who practice self-care may experience less stress and greater emotional resilience. Self-care practices such as getting enough sleep and managing chronic health conditions can improve cognitive function in older adults. These can help prevent or delay the onset of cognitive decline and dementia. Finally, self-care promotes independence for older adults. By taking care of themselves, they can maintain their independence and avoid relying on others for assistance with daily activities.
As with other age groups, health education classes can cover various topics useful for self-care of older adults, including nutrition, exercise, medication management, and stress management. Older adults can also benefit from one-on-one counseling sessions focusing on their self-care needs and goals. During such sessions, a nurse can provide guidance and support on healthy habits, medication adherence, and chronic disease management. Group support programs may also be beneficial, as they provide a sense of community and encouragement. The group may focus on a specific condition or a specific health behavior. Technology-based educational interventions may also be beneficial with older adult populations. Applications used on smartphones or websites may provide information on healthy living or assist in tracking of activities such as sleep or medication management. Finally, nurses may make home visits to older adults to provide education and support regarding self-care practices. This may be particularly useful for those who have limited mobility or live in rural areas.
Healthy People 2030 Goals for Older Adults
The overarching Healthy People 2030 goal for older adults is to “improve health and well-being for older adults” (ODPHP, n.d.-f, para. 1). Their prediction is that by 2060, almost a quarter of the U.S. population will be older adults. As such, the focus is on the issues this population experiences related to their health and SDOH.
Healthy People 2030 older adult objectives are in a variety of categories and address topics such as physical activity, dementias, foodborne illness, infectious diseases, reduction of hospital admissions (for pressure ulcers, diabetes, urinary tract infections, pneumonia, and asthma), injury prevention related to falls or the use of inappropriate medications, oral conditions, osteoporosis, and age-related macular degeneration vision loss.
One focus area of Healthy People 2030 is falls in older adults. One in three fall annually, and falls are a leading cause of injury for this population. ODPHP (n.d.-h) has recognized that physical activity can help older adults prevent chronic diseases and fall-related injuries. Objectives related to increasing the proportion of older adults with physical or cognitive health problems who get physical activity, reducing the proportion of older adults who use inappropriate medications, reducing hip fractures among older adults, and increasing the proportion of older adults who get screened for osteoporosis can help to address falls. Unfortunately, fall-related deaths among older adults is getting worse. In 2018, there were 64.4 deaths per 100,000 caused by unintentional falls and 78 deaths per 100,000 in 2021. The target is a decrease to 63.4 per 100,000 (ODPHP, n.d.-h).
Health Promotion and Disease Prevention Activities to Improve the Health of Older Adults
Heath promotion for older adults often requires a multidisciplinary approach that includes nurses, other health care professionals, community organizations, and caregivers. Health promotion activities to improve the health of older adults should be geared toward the major diseases that impact them. Regular physical activity can help older adults maintain a healthy weight, increase their strength and flexibility, reduce their risk of falls, and improve their overall health and well-being. Activities promoting a balanced and healthy diet can help with healthy weight maintenance, reduce the risk of chronic diseases, and improve overall health. Other health promotion activities that can improve the health of older adults include:
- Promoting clients to remain active, independent, and involved in their communities as long as possible
- Providing resources to help caregivers of older adults stay healthy and deliver quality care
- Providing resources for senior centers in communities
- Promoting fall prevention programs in the home and in the community
- Promoting maintenance of appointments with providers for medical management of chronic conditions
One example of a national health promotion activity is SilverSneakers (Tivity Health, 2023). This fitness program is available for older adults enrolled in Medicare Advantage Plans (Part C) at over 17,000 locations, including national gym franchises, community centers, and senior centers. SilverSneakers also offers online workout videos for those who prefer to work out at home or are homebound. Classes range from balance and stability lessons and gentle stretches to Pilates, cardio and strength, line dancing, and kickboxing. Yoga, mindfulness, meditation sessions, and a fitness application for smartphone use are also offered. Daily tips on the SilverSneakers blog provide information on nutrition, diseases and conditions, and physical activity tips.
Caregivers who assist older adults are essential members of public health care. While some caregivers are hired, informal or unpaid caregivers provide a substantial portion of long-term care in homes across the United States. These unpaid family members or friends are typically middle-aged or older adults who may perform a range of tasks, such as assisting with activities of daily living, helping to manage a chronic disease or disability, paying bills, shopping, providing transportation, or providing emotional support. Caregivers may initially have few responsibilities, but as the recipient’s care needs increase, additional responsibilities may increase, leading to a strain on the caregiver.
The need for caregivers is an important public health issue. In 2019, the CDC indicated that there were seven potential family caregivers per older adult, but by 2030, there will only be four potential family caregivers per older adult. According to the CDC (2019b), 22.3 percent of adults reported providing care or assistance to a friend or family member in the past 30 days. Among adults aged 45 to 64 years, 24.4 percent were caregivers, compared to 18.8 percent of adults aged 65 years and over. One in four (25.4 percent) women were caregivers, compared to one in five (18.9 percent) men. Black people comprised the largest percentage of caregivers (24.3 percent), followed closely by White people (23.1 percent), then 17.9 percent of Hispanic people and 10.2 percent of Asians/Pacific Islanders. One in three caregivers provided 20 or more hours per week of care, and over half provided care or assistance for 2 years or longer.
Caregiving can provide great satisfaction and strengthen relationships between families and friends. It can also negatively affect the caregiver’s ability to work, engage in social interactions and relationships, and maintain good physical and mental health (CDC, 2019b). Therefore, health promotion and disease prevention of older adults must be geared to the recipient of care and the caregiver. The CDC (2019b) recommends the following for health care professionals engaging in health promotion and disease prevention of the older adult population:
- Increase messaging regarding the importance of caregivers and of maintaining their health and well-being
- Educate about the importance of caregiving before caregivers begin
- Provide caregivers with resources and supports
- Be mindful of the health risks for caregivers, encourage them to use available information and tools, and make referrals to supportive programs and services as applicable
- Assist with caregiver training and support programs
- Advocate for awareness of and access to evidence-based programs and services that can help caregivers and care recipients
- Encourage caregivers to get regular checkups, use preventive services, and engage in self-care to maintain their physical and mental health
- Ensure that caregivers with a disability and/or chronic disease have access to self-management programs to maintain their health (para. 13)
Along with providing education and support for caregivers, population health nurses must be aware of potential elder abuse. Elder abuse is an intentional act or failure to act that causes or creates a risk of harm to an older adult and occurs in about 1 in 10 people aged 60 and older who live at home (CDC, 2021g). The abuse occurs at the hands of a caregiver or a person the elder trusts, and it can involve physical, sexual, emotional or psychological, or financial abuse; neglect; or a combination of these (see Table 26.12). Prevention of elder abuse can begin by understanding and addressing the factors that put them at risk for or protect them from violence. See Caring for Families for more information on preventing elder abuse.
| Risk Factors for Perpetration of Elder Abuse | |
| Individual Risk Factors |
|
| Relationship Risk Factors |
|
| Societal Risk Factors |
Specific characteristics of institutional settings, such as nursing homes and residential facilities, including:
|
| Protective Factors for Victimization | |
| Individual Protective Factors |
|
| Relationship Protective Factors |
|
| Community Protective Factors |
|
| Mechanisms Nurses Can Use to Prevent Elder Abuse | |
|
Evidence-based practice is important to health promotion and disease prevention for older adults. While the Institute for Healthcare Improvement’s (IHI, n.d.) Age-Friendly Health System initiative was designed originally for hospital and clinical settings, population health nurses can also use the concepts. In this video, Dr. Mary Tinetti, Chief of Geriatrics at the Yale School of Medicine and Yale-New Haven Hospital, describes the components of an age-friendly health system.
Watch the video, and then respond to the following questions.
- What does it mean that older adults become more heterogeneous as they age?
- Why were the 4Ms chosen as concepts in the age-friendly health system?
- What are the 4Ms in the age-friendly health system?
- What nursing interventions could be implemented to address each 4M?
Primary Prevention
Primary prevention strategies typically focus on maintaining the health of healthy older adults and preventing the development of chronic diseases and frailty. Examples of primary prevention (Lenartowicz, 2022) include:
- Immunizations, such as the influenza, pneumococcal, tetanus, and zoster vaccines
- Chemoprevention using aspirin for the prevention of coronary heart disease and stroke, if applicable
- Lifestyle changes, such as smoking cessation, avoidance of trans fats, increased intake of fruits and vegetables, moderate physical activity, adequate calcium and vitamin D intake, and limited caffeine and alcohol intake
- Specific recommendations for prevention of frailty including exercise and a low-fat, reduced sodium, high-calcium, high-fiber diet with calcium and vitamin D supplements
Secondary Prevention
Secondary prevention of disease in the older adult population aims to detect and treat disease or its complications before symptoms or functional losses occur. An older adult may have minimal or no chronic disease but require secondary prevention. The primary method of secondary prevention is screening. Multiple organizations publish screening guidelines, which can differ. The following are Medicare-covered preventive service guidelines for older adults (Highmark, 2023b):
- Weight, height, and BMI monitoring annually
- Blood pressure screening annually
- Lipid panel every 5 years or as clinically indicated
- Fasting plasma glucose in those who are overweight or obese annually
- Mammography every 1 to 2 years until age 75
- Chlamydia and gonorrhea screening for older women who are at increased risk for infection
- Syphilis, HIV, and hepatitis B screening for those at increased risk for infection
- Hepatitis C screening
- Colorectal cancer screening until age 75
- Bone mineral density screening of women aged 65 to 69 years and men aged 70 years and over every 2 years
- Prostate cancer screening for men aged 55 to 69 years, if clinically indicated
- Lung cancer screening for those aged 50 to 80 years who have a 20 pack-year smoking history and currently smoke or have quit within the past 15 years
Another secondary prevention important for older adults is screening for fall risk. As mentioned, the CDC’s (2023h) STEADI provides a coordinated approach for nurses and other health care providers to implement the practice guideline for fall prevention. Videos for health care providers and older adults can be viewed on the CDC website.
The community health nurse should teach older adults or their caregivers to do the following:
- Keep emergency numbers at hand, including 911, poison control, a family member or friend’s number to call in case of emergency, and the health care provider’s office number.
- Consider a special alarm that can be worn as a bracelet or necklace. The button can be pushed in case of a fall, and emergency services will be notified.
- Try not to rush to answer the phone. Carry a cordless or cell phone when moving around the home, or let an answering machine pick up messages.
- Wear nonslip footwear, such as slippers with rubber/no-slip bottoms or flat, thin-soled shoes that fit well.
- Use a cane or walker, if needed, rather than relying on holding on to walls or furniture.
- Make sure all hallways, stairs, and paths are well-lit and clear of any objects such as books or shoes.
- Use rails and banisters when going up and down stairs. Never place scatter rugs at the bottom or top of stairs.
- Tape all area rugs to the floor so they do not move when walking on them.
- If there is a fire in the home, leave immediately and call 911. Do not attempt to put a fire out.
- Do not wear loose clothes or long sleeves when cooking.
- Replace appliances with frayed or damaged electrical cords.
- Do not put too many electrical cords into one socket or extension cord.
- Ensure smoke detectors are installed and batteries are changed twice a year.
- Never smoke in bed or leave candles burning, even for a short time, in an empty room.
- Make sure heaters are at least three feet away from anything that can burn, such as curtains, bedding, or furniture. Turn off space heaters when leaving a room.
- Set the water heater thermostat no higher than 120°F to prevent scalding.
- Have grab bars installed in the shower and near the toilet.
- Put rubber mats in the bathtub to prevent slipping.
- Consider a special tub/shower chair or raised toilet seat if there are difficulties with getting in and out of the tub, standing for long periods in the shower, or getting on or off the toilet.
- Never try to heat the home with the stove, oven, or grill.
- Place a carbon monoxide detector near all bedrooms, and test and replace the battery twice a year.
- Keep all medications in their original containers to prevent mix-ups.
- Ask the pharmacist to put large-print labels on medications to make them easier to read.
- Take medications in a well-lit room so that labels can be easily seen.
- Never mix bleach, ammonia, or other cleaning liquids together when cleaning.
- Keep windows and doors locked at all times.
- Never let a stranger into the home when they’re alone.
- Talk over offers made by telephone salespeople with a friend or family member.
- Do not share personal information, including Social Security number, credit card or bank information, or account passwords, when contacted by unknown individuals.
- Always ask for written information about offers, prizes, or charities and wait to respond until the information has been thoroughly reviewed.
- Do not feel pressured into making purchases, signing contracts, or making donations before discussing with a family member or friend.
(See Health in Aging Foundation, 2019.)
Depression screening is important in identifying social isolation in older adults. If clients feel lonely or isolated, they may benefit from assistance in increasing social contacts to prevent morbidity. Those who are depressed warrant appropriate intervention. Older adults should be encouraged to remain as productive as possible, engage in leisure activities, and maintain a sense of social connectedness in order to help prevent psychosocial problems and physical disability (Lenartowicz, 2022).
Tertiary Prevention
Tertiary prevention is designed to manage an existing, symptomatic, and typically chronic disease to prevent further functional loss. Older adults with the following chronic disorders can potentially benefit from tertiary prevention:
- Arthritis to prevent progression or falls
- Osteoporosis to prevent progression or fractures
- Diabetes to prevent retinopathy, neuropathy, nephropathy, coronary artery disease, and foot ulcers or amputation
- Vascular disorders to prevent disabling events such as myocardial infarction or stroke
- Heart failure to reduce functional decline, hospitalization, and mortality
- COPD to decrease the number and severity of exacerbations and the need for hospitalization (Lenartowicz, 2022)
As with the adult population, disease-specific care management programs are useful in addressing these disorders. Chronic care clinics and specialists may also be used with older adults. Interventions to address polypharmacy, mentioned earlier, are also considered tertiary prevention. Medication reconciliation is an excellent mechanism for preventing difficulties resulting from polypharmacy (Coppard et al., 2019).
Integration of Sociocultural and Linguistically Responsive Interventions for Older Adults
Integrating sociocultural and linguistically responsive interventions for older adults promotes health equity and improves health outcomes. This section has described the older adult population’s diverse ethnic backgrounds and recognized that health disparities exist among older adults, such as high rates of chronic diseases, particularly among older adults from certain racial and ethnic backgrounds. Access to care is often also impacted. While social isolation may be a significant concern for many older adults, it is particularly difficult for those from cultural minority groups. Additionally, older adults or their caregivers may have unique health needs related to their cultural backgrounds. By integrating sociocultural and linguistically responsive interventions, nurses can better address the needs of this population, improving their health outcomes and quality of life.
Sociocultural Interventions
Social connections and supports are essential for healthy aging, but these may be affected by the sociocultural environment, particularly a community’s values and beliefs. Howell (2020) performed a study to examine the relationship between the sociocultural factors that shape diet, physical activity, and nutritional status outcomes among Alaska Native and African American Alaskan older adults. The study found that participants’ diet and physical activity practices did not meet national recommendations. Howell (2020) also found that incorporating friends in interventions led to increased energy expenditure in participants, and family members influenced increased fruit consumption. Participation in cultural social events increased participants’ intake of fats and sweets. The media was also found to be a strong influencer of participants’ behavior, as 85.4 percent reported daily television watching, and was recommended as a way to reach older adults with socioculturally responsive programs to alleviate some of the barriers to healthy diet and exercise (Howell, 2020).
Older adults also frequently experience pain. Reis et al. (2022) described the importance of recognizing cultural factors’ influence on how individuals perceive, respond to, communicate, and manage pain. Pain education should be provided using different culturally appropriate examples, metaphors, images, and delivery methods. Reis et al. found that a culturally sensitive educational session require a good communicator who will listen to client concerns, recognize the legitimacy of their pain, and respect their culture, values, and preferences. Failure to do this negatively impacts the educational session. The nurse should assess a client’s beliefs about pain, as these may range from pain being a normal part of aging to being a punishment from a higher power for bad deeds. Reis et al. (2022) recommend using several different audiovisual aids, including those the client can take home to share with friends and family.
Linguistically Responsive Interventions
Language barriers can limit access to health care in any population. Older adults who speak a language other than English may face language barriers that limit their ability to understand their disease or even access health care services. The National Council on Aging (2022) spotlighted a senior center in Nebraska that served seniors with language barriers. The members of the Intercultural Senior Center (ISC) spoke over 15 languages, including Spanish, Korean, Nepali, Karenni, and Burmese, and ISC staff included individuals from at least 10 different countries who spoke a variety of languages. Specific services offered by ISC included linguistic and cultural accessibility, access to and navigation of legal and health services, transportation, and social engagement (National Council on Aging, 2022).